Mixing head



June 16, 1959 J. A. POTCHEN MIXING HEAD Filed Aug. 1, 1955 mummi- IN VEN TOR. Joseph 4. Pair/zen MIXING HEAD Joseph A. Potchen, Marne, Mich.,assignor, by mesne assignments, to Haskelite Manufacturing Corporation,a corporation of Delaware Application August 1, 1955, Serial No. 525,748

6 Claims. (Cl. 259-4) States Patent 9 is solved by the batch method inwhichtbe substances are placed together and then by agitation or similarmechanical means mixed one into the other until a complete blending ofthe two substances hasbeen efiected.

Where the substances are miscible and both have a low viscosity, such aswater, the problem is not particularly serious. Where, however, thesubstances are immiscible the task of blending presents a difiicultproblem. Also, where one or both of the substances is characterized byeither a high viscosity or high surface tension, the problem becomes aserious one if the desired result is a complete blending to the extentthat the individual characteristics of both substances become entirelylost and unidentifiable.

The problem becomes even more acute where the mixing must be donecontinuously and rapidly. In some cases, a further complication isintroduced by the necessity of eifecting the mixing either in an inertatmosphere or completely isolated from gaseous contact to preventchemical reactions or the entry of the gases into the substances.

All of these problems are presented in acute form in the use of theso-called foaming diisocyanate plastics. In this case the substancesareof different viscosity and different surface tension and are notreadily miscible. Further, since the chemical reaction producing thefoaming actionis initiated normally within a matter of seconds after thesubstances are brought into contact, the complete mixing operation mustbe carried out rapidly to'elfect complete blending before the foamingreaction sets in. l V

Further, it is desirable thatthe mixing of the substances be carried outin such a manner that no air becomes intermixed into the substancesduring the mixing and blending operation. Despite the rigid conditionsunder which the mixing must occur, it is absolutely essential that themixing of the reactants making up the foaming diisocyanate' plasticseffect a complete blend so that all characteristics of the individualsubstances are completely obliterated.

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viscosity or surface tension. It provides a method and means ofcontinually mixing such substances to produce a complete blend. It alsois characterized by adaptabili ity to all of the specialized anddiflicult conditions-imposed upon this type of operation. A

These and other objects and purposes of this invention will beimmediately seen by those acquainted with the problems of blendingflowable substances upon reading the following specification and theaccompanying drawings.

In the drawings:

Fig. 1 is a side elevation view of a mixer embodying the principles ofthis invention.

Fig. 2 is a bottom view of the discharge head for the. mixer.

Fig. 3 is a central sectional elevation view of the mixer.

Fig. 4 is a plan view of one of the mixing disks or bafiies utilized inthe mixer.

Fig. 5 is a bottom view of the mixing disk illustrated in Fig. 4., i p

Fig. 6 is a plan view of a modified form of the mixing disks illustratedin Fig. 4.

Fig. 7 is a sectional elevation view taken along the plane VII-VII ofFig. 4.

Fig. 8 is a sectional elevation view taken alongthe plane VIIIVIII ofFig. 4.

Fig. 9 is a sectional view taken along the plane IX- IX of Fig. 3.

Fig. 10 is a sectional view taken along the plane X-X of Fig. 3 showinga modified arrangement for the mixer. Fig. 11 is a plan view of anothermodification of the disk.

In executing the objects and purposes of this invention, I have provideda mixing head in which two or more fiowable substances are broughttogether and then passed into a chamber from the center of which theyare withdrawn in the form of two or more small streams. These streamsare introduced into a second chamber in such a manner as to circulate inthe form of a whirlpool, thus effecting an intermixing of thesubstances. The substances are then withdrawn from the center of thiswhirlpool in the second chamber and divided into two or more separatestreams. These streams are again reintroduced into a third chamber toform a whirlpool. This process is repeated until the substances areentirely blended.

of the individual streams. The separate pieces are then Since, in manycases, the mixed substances form re-mixed so that the individual piecesof each substance become thoroughly intermixed by twisting them togetherin the manner of a rope. By repeating this uniting by twisting, cuttingand reuniting by twisting the cut-off portions, the substances becomecompletely blended. Referring specifically to the drawings, the numeral10 indicates a mixing head having a shell 11, the upper end of which isclosed. The lower portion of the shell is hollow, providing a mixingcavity 12, connected to a receiving cavity 13 by a pair of passages 30.In the particular embodiment illustrated in Figs. 1 and 3, the receivingcavity 13 extends diametrically through the head and is threaded on eachend to provide a pair of receiving ports 14 and 14a. As will be morefully explained hereinafter this is but one of many possiblearrangements which may be used to introduce the substances to the mixer.

While this invention is particularly described. as having apair ofreceiving ports for admitting the flowable substances, it will berecognized that if more than two substances are involved, additionalreceiving ports may be provided as is indicated in Fig. 10. In shell 11athree receiving ports 14b, 14c and 14d are shown tangentially enteringthe mixing chamber 13a. The mixing cavity 12 can be extended up into thearea of the receiving ports with the upper portion of it forming thereceiving cavity 13a and the passages 30 eliminated.

Again referring to Fig. 1, a pair of supply conduits 15 and 15a areconnected to the receiving ports 14 and 14a respectively. Normally,supply conduits 15 and 15a have a control valve 16 and 16a respectivelyand a pump 17 and 17a respectively. By means of either the capacity ofthe pumps 17 and 17a or the adjustment of the valves 16 and 16a or both,the relative quantities of the substances entering the mixer may beaccurately proportioned. While this is one particular method ofproportioning the relative volumes of the two sub stances, others may beemployed.

It will be recognized that a pre-mixing operation may be carried outbetween two of the substances and then the mixed substances introducedtogether with a third substance to be blended within this mixer. Foreifecting this pre-mixing of certain of the substances a mixer 10 may beused. Thus, two or more of these mixers may be used in tandem.

A spacer ring 20 bearsagainst the upper end wall 21 of the cavity 12.The spacer ring 20 creates a receiving chamber at the upper end of themixing cavity 12 into which the substances may flow from the passages14. In a construction in which the passages 14 are eliminated and thereceiving cavity 13 is but an extension of the mixing cavity 12, thering 20 can be eliminated. However, it is essential that the diameter ofthe interior cavity of the shell 11 be reduced at this point to form ashoulder against which the upper or first of the mixing disks 22 may beseated.

' 'Ihe wafers or mixing disks 22 are designed to slidably but closelyfit within the cavity 12. The fit should be such that there will be notendency for the substances to by-pass the disks between their peripheryand the walls of the cavity 12. In the illustrated form of thisinvention, five mixing disks are utilized. It will be recognized thatthe number of mixing disks used in the mixer will depend upon theparticular characteristics of the substances being mixed and thediificulty with which they are blended. Thus, if the substances areexceedingly difficult to blend, more of the mixing disks may be usedwhereas if the substances are relatively easy to blend, a lesser numberof the mixing disks may be used.

The individual mixing disk has a small, blind chamber or well 23 in thecenter of its upper face. Extending radially from the well are threechannels 24 having a receiving portion 26 and a discharge portion 25.The receiving portions 26 of these channels extend radially outwardlythrough the periphery of the disk. The diameter of each channel is suchthat it has sufiicient capacity to pass approximately one-third of theexpected flow rate of the material. Each of the channels 24 has adischarge portion 25 communicating with the receiving portion 26adjacent the periphery of the disk. The discharge portion 25 is inclineddownwardly and communicates with the recess 29 in the bottom of thedisk. The discharge orifices of the channels 24 are so oriented thatthey enter the recess 29 tangentially to a theoretical circle adjacentthe periphery of the recess. The recess 29 is, in efiect, a blind cavitymilled into the lower surface of the disk and having a diameterconstituting the major portion of the diameter of the disk. The recess29 is surrounded by a wall 27 which, in effect, spaces the top wall 28of the recess above the top surface of the next adjacent disk to createthe chamber 29.

The channels preferably are equally spaced and the discharge orifices ofthe channels in the recess 29 are likewise equally spaced. By extendingthe channels through the periphery of the disk, both portions are madeaccessible for cleaning by the insertion of a rod from the periphery ofthe disk.

It will be recognized that the disks 22a may be so designed that thechannels 24a do not breach the periphery of the disk (Fig. 11). Thesechannels 24a are so curved that, while they leave the central well 23radially, they enter the recess 29 tangentially adjacent its periphery.It is important that the channels discharge tangentially into the recessto create the whirlpool type of movement in the recess.

The channels 24 or 24a may communicate tangentially with the centralwell. Both the radial and tangential arrangements cause effectivesubdivision of the substances entering the well.

In the particular embodiment illustrated in Fig. 3, five disks 22 areutilized. These disks are enclosed by a discharge head 35. The head hasan internally threaded recess in one face, providing the means ofattachment to the shell 11 since, on its lower end, the shell isthreaded; The head 35 has, at its center, a discharge orifice 36 throughwhich the blended substances are discharged.

The components of the mixer 10 may be fabricated from any suitablematerial. Such material must have sufficient strength to withstand theoperating pressures of the mixer. They must be inert in the presence ofthe substances passed through the mixer. An example of one particularmaterial normally suitable for this puipose is brass.

Operation The substances to be mixed are first brought together in thereceiving cavity 13. Slight mixing may occur in this cavity but normallysubstances of the type with which this mixer is intended to be usedstrongly resist intermixing. Consequently, the substances will pass fromthe receiving cavity to the first mixing disk in completely identifiableform.

After entering the mixing cavity 12, the substances flow into thecentral well 23 of the top or first disk 22. As the substances flow outof the well 23, they are divided into three separate streams by passinginto the individual channels 24. The substances are discharged fromthese channels into the first recess or mixing chamber 29. As thesubstances enter the recess or mixing chamber 29, they are caused tospiral within the chamber by reason of their tangential entry. Thisspiraling tends to mix the substances and to intermix the individualstreams by rolling them to some extent about each other in the form of arope. The substances move inwardly in the chamber 29 in the form of awhirlpool and discharge at the center through the well 23 of the seconddisk. From this well the mixed substances are again divided into threeindividual streams upon entering the channels 24 of the second disk. Thesubstances discharge tangentially from the channels 24 of the seconddisk into the second mixing chamber 29. Here they are again reunited ina whirlpool with the individual streams twisting about each other. Thisprocess is repeated by each mixing disk 22 seated in the mixing cavity12.

The result of this arrangement is to treat the sub stances much in themanner in which a rope is manufactured. The substances are first dividedinto two more individual streams. These streams are then reunited bytwisting them about each other in the form of'a rope. This is the actionoccurring in the first mixing chamber 29. The reunited and twisted massis then cut into random sections by its entry into the individualchannels 24 of the second disk. This, in effect, is cutting the twistedrope form into short pieces which pieces, when reunited, in the secondmixing chamber are arranged in a random pattern. This results inthorough intermixing. This random pattern of pieces is again spiraled inthe second mixing chamber to form a rope. It will be seen that theprocess of dividing and subdividing of the individual substancesprogresses arithmetically as they pass through the mixer. This action iscontinued until the individual characteristics of each separate piece islost and the substance as a whole has acquired the characteristics of atrue blend.

This mixer is specifically designed for the handlin of diflicult to mixflowable substances. Thus, it is designed to handle substances which areimmiscible and which are not readily soluble one within the other. As anexample, it is designed to blend such immiscible substances as oil andwater or in a paint to blend the pig ment, vehicle and carrier to form ablend in which the individual characteristics of each ingredient have become indistinguishable. I

This mixer is capable of completely blending such substancesirrespective of their lack of solubility, their lack of miscibility andthe fact that each substance is characterized by high surface tensionand high viscosity. It will be recognized that this mixer is quitecapable of mixing a large number of individual, flowable substances andis' not limited to the mixing of merely two or three such materials. Itmay be, in cases where a number of substances are brought together, thatthe proportional size of the mixer will have to be increased to providesufficient flow through the mixer. It will be recognized that theoverall size of the mixer may be changed to meet the requirements ofparticular situations. In these cases it may also be necessary toincrease the number of individual mixing disks 22 to elfect completeblending of the materials. Another modification which will increase themixer flow capacity is increasing the number of channels in each disk.These, however, are merely multiplications of the principle employed inthe mixer illustrated.

The relative diameters of the channels 24 and of the wells 23 may varywithin a considerable range and still effect the mixing action. This istrue because the mixer effects blending by twisting, separating andrandom rearrangement of the substances and not upon any turbulencecreated within the flowing substances as they pass through the channelsand orifices. Tests have indicated that the creation of turbulencewithin substances of this type will not cause mixing such as is producedby this machine. The inability to mix and blend substances of this typeby turbulence is established by the fact that when two heavy, saturated,sugar syrups each identified by a distinct coloring were passed at roomtemperature through a one-sixteenth, internally tapped, three inch longorifice, they failed to mix and were discharged in clearly identifiableindividual streams.

These same substances passed through this mixer, utilizing five disks inwhich the wells 23 were one-eighth inch diameter and the channels 24were five sixty-fourths inch diameter, the syrups were so completelyblended that the individual colors of each syrup had become entirelyindistinct. These sugary syrups were passed through the mixer atapproximately the rate of one quart per minute under a pressure of fromone hundred to three hundred pounds per square inch.

Among other substances which have been successfully blended with thismixer are a polyester resin and a diisocyanate. These substances are notmiscible and are resistant to intermixing. Yet a five disk mixer ofidentical construction as that used for the heavy sugary syrup effecteda complete blending of these substances.

It will be recognized from this description that the particular size ofthe channels 24, wells 23 and the discharge orifice 36 is notparticularly critical. These are chosen to be of sufficient size topermit the substances to be passed through without too great aresistance and at a flow rate which will meet the demand requirements ofthe particular application.

The lower limit of size of the channels is established by the upperlimit of back pressure it is practical to create within the mixer. Theupper limit of the channel size is set by that which will causesufficient division of the substances to effect a complete blending.

It will be recognized, however, that this, again, is a relative matterinasmuch as a mixer having a certain number of disks, each equipped witha particular diameter of channel, which will not effect completeblending can be made to do so by increasing the number of disks throughwhich the material is passed or the number of channels in each disk.Also, ditficulty along this line may be overcome by increasing thenumber of channels 24 in each disk. These changes are'merely matters ofroutine design adaptation since the basic principles of the method andstructure disclosed by this invention are employed.

It is necessary that at least two channels 24-be provided in each mixingdisk. However, the number of channels 24 in excess of two is a matter ofdesign choice. Thus, designs having six or more such channels are en-'tirely effective. v 7

Where it is felt desirable, left and right hand disks may be arranged inan alternate pattern to cause the substances to spiral in oppositedirections. Preliminary tests on this arrangement have indicated that itdoes not materially increase the e'tficiency of the mixer, at leastunder the circumstances in which the mixer has been presently used. Itis thought that some slight rotation of the disks may occur as a resultof the passage of the substances through them. This is not believed tohave any detrimental effect upon the operation of the mixer. Byalternately arranging right and left hand disks this rotation effect maybe counteracted.

Since the mixer is useable either as the discharge head or as aninsertion in a conduit at the juncture of the conduits for theindividual substances, it is adapted to continuous operation. Further,since the substances are confined to a closed chamber during the mixingin which there is no air or other gaseous medium, it is ideally suitedto the mixing of substances which must not have contact with gasesduring the mixing operation.

The mixer may be quickly and easily cleaned by passing a suitablecleaning liquid through it. This may be done by providing an additionalinlet port in the receiving cavity through which the cleaning liquid isadmissible. This is particularly advantageous in connection withsubstances which do not require thorough removal at the end of eachoperational run except in zones where they have been mixed.

It will be recognized that various modifications of this invention maybe made such as the alternate use of right and left hand disks or theuse of the type of mixing disk illustrated in Fig. 11. The disks may bemade integral with the housing in the form of bafiles. Each of thesemodifications, however, will employ the principles of this invention.Accordingly, such modifications are to be considered as included in thehereinafter appended claims unless these claims by their languageexpressly state otherwise.

I claim:

1. A mixer for mixing flowable substances comprising a housing, a diskin said housing defining a first recess on one side thereof, an inletport communicating with said first recess, a plurality of channels insaid disk communicating with said inlet port extending radially to theperiphery of said disk and a plurality of channels communicating withsaid radially extending channels and extending inwardly and terminatingadjacent to the periphery of a second recess disposed on the side ofsaid disk opposite to the side containing said inlet port, said secondrecess having a diameter smaller than the diameter of said disk, andclosing means in said housing closing said housing, and port means insaid closure means communicating with said second recess.

2. A mixer in accordance with claim 1 wherein said housing encloses aplurality of said disks.

3. A mixer for flowable substances comprising a housing having a centralchamber, an inlet port communicating with one end of said chamber, adisk seated in said chamber and engaging the walls thereof, saiddiskrhavin-g a central blind opening in the one face adjacent said inletport, at least a pair of channels in said disk communicating with saidopening and extending outwardly away therefrom, said disk having arecess in its other face, and said channels communicating tangentiallywith said recess adjacent the periphery thereof.-

4. A mixer as recited in claim 3 wherein a plurality of said disks aremounted in said housing and including means for pressing said diskstogether.

5. A disk element for a mixer for flowable substances comprising a bodymember having a central blind opening in one face and a recess in theother face, said recess being surrounded by a spacer wall, a pair ofchannels each communicating at one end with said blind opening, and theothers of the ends of said channels communicating tangentially with saidrecess adjacent said spacer;- wall. r

6. A disk elementfor a mixer for flowable substances comprising a bodymember having a central blind open; ing in one face and a recess in theother face, surrounded by'a spacer wall, a first plurality of'channelseach com; municating at one end with said blind opening, said channelsextending radially from said blind opening -'to the periphery of saidbody member, and a second plurality of channels each at one endcommunicating with one of said first plurality of channels adjacent theperiphery of said body member and at the other end communieatingtangentially with said recess.

References Cited in the file of this patent UNITED STATES PATENTS1,405,707 Beers Feb. 7, 1922 2,561,457 Beales et a1. July 24, 19512,647,732 Jarman Aug. 4, 1953

